You are here

Climate Data

The AMSR-E/NASA Team 2 (NT2) data set of Arctic and Antarctic sea ice concentration is available at daily timesteps and 12.5 km (optionally 25km) spatial resolution for 2002-2011. NT2, an extension of the original NASA Team algorithm, uses AMSR-E 89GHz channels to help resolve ambiguity between low ice concentrations and areas with strong surface effects (due to snow layering and glazing). 89GHz channels introduce more weather contamination. NT2 implements a radiative transfer model to filter for weather that simulates brightness temperatures under several idealized polar atmospheres. The algorithm searches for the best fit between the observed and modeled brightness temperature ratios to pick the final concentration. Unlike ASI, NT2 uses the lower frequency channels as well as the high frequency channels. Sea ice from NT2 is more similar to Bootstrap sea ice than was the original NASA Team sea ice. Some differences are still apparent; NT2 usually shows slightly higher concentrations in the Antarctic and more sensitivity to thin ice. The NSIDC data set also includes estimates of snow depth on sea ice and of bootstrap sea ice retrievals.

Key Strengths:

Addresses weaknesses of the original NASA Team algorithm, especially with regards to sensitivity to emissivity variations. This leads to significant improvement in the Antarctic.

Twice the spatial resolution of most other passive microwave sea ice data sets; useful for comparing with high-resolution models

Provides independent verification of sea ice climatologies and trends in the recent decade compared to SSM/I and SSMI/S data

Key Limitations:

Not currently being updated; AMSR-E failed in Oct, 2011

Potential sensitivity of NT2 to weather effects as it uses the 89GHz channel

Acknowledgement of any material taken from this page is appreciated. On behalf of experts who have contributed data, advice, and/or figures, please cite their work as well.

The AMSR-E/NASA Team 2 (NT2) data set of Arctic and Antarctic sea ice concentration is available at daily timesteps and 12.5 km (optionally 25km) spatial resolution for 2002-2011. NT2, an extension of the original NASA Team algorithm, uses AMSR-E 89GHz channels to help resolve ambiguity between low ice concentrations and areas with strong surface effects (due to snow layering and glazing). 89GHz channels introduce more weather contamination. NT2 implements a radiative transfer model to filter for weather that simulates brightness temperatures under several idealized polar atmospheres. The algorithm searches for the best fit between the observed and modeled brightness temperature ratios to pick the final concentration. Unlike ASI, NT2 uses the lower frequency channels as well as the high frequency channels. Sea ice from NT2 is more similar to Bootstrap sea ice than was the original NASA Team sea ice. Some differences are still apparent; NT2 usually shows slightly higher concentrations in the Antarctic and more sensitivity to thin ice. The NSIDC data set also includes estimates of snow depth on sea ice and of bootstrap sea ice retrievals.

The National Center for Atmospheric Research is sponsored by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.